Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRATED PRESSURIZED PUMP SHAFT SEAL ASSEMBLY AND
METHOD OF USE THEREOF
1. TECHNICAL FIELD
The present invention relates generally to pump shaft seals and methods of use
thereof.
More specifically, the present invention relates to pump shaft seal assemblies
such as for
submersible or semi-submersible pumps which are adapted to be pressurized by
an integrated
seal pressure pump, and methods of use thereof.
2. BACKGROUND OF THE INVENTION
Rotary fluid pumps are typically prone to malfunction and/or failure due to
seal failure,
such as failure of seals around the pump shaft that typically seal against
ingress of pumped fluid
into pump shaft bearings and/or a pump motor such as a typical electrical pump
motor.
Particularly in rotary pumps that pump abrasive fluids and slurries, wear of
pump shaft seals and
eventual failure of the shaft seals may be accelerated or worsened, leading to
premature or
undesirably frequent requirement for repair, servicing and/or replacement of
pumps. Such
undesirable pump malfunction and/or failure may result in expensive downtime
and
maintenance, leading to lost time and expense.
In some submerged pumps known in the art for operation at significant depths,
pressure
compensated seals may be used typically requiring external sources of air or
other fluid pressure
to balance pressures on both sides of pump seals. Such typical external
pressure sources known
in pressure compensated submerged pumps may undesirably add complexity and
expense and
require reliance on pressure compensation equipment external to the pump
system which may be
undesirable in many applications where lower cost, reliability and simplicity
are desirable.
Accordingly, there remains a desire for improved rotary pump seals and methods
for their
application that address some of the limitations of the pump seals known in
the art.
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3. SUMMARY OF THE INVENTION
It is an object of the present invention to provide an integrated pressurized
pump seal
assembly that addresses some of the limitations of the prior art.
It is a further object of the present invention to provide a method of using
an integrated
pressurized pump seal assembly that addresses some of the litnitations of the
prior art.
In one embodiment, an integrated pressurized pump seal assembly pump design
may be
provided that desirably substantially prevents a pumped fluid, such as an
abrasive fluid or slurry
from seeping up the rotating pump shaft to the pump shaft bearings by leakage
through a lower
seal, such as a typical mechanical shaft seal. Mechanical seals may typically
leak a small amount
of oil or other seal lubricating fluid by the nature of the mechanical seal
design and may typically
be prone to system upsets. In one embodiment according to the present
invention, a self-
pressurized pump seal chamber is provided in an integrated pressurized pump
seal assembly,
wherein the oil within the pump seal chamber may desirably be maintained at a
pressure greater
than the sump pressure of the surrounding pumped fluid. Therefore desirably
grit, moisture
and/or other contamination cannot enter and damage the seal assembly under
standard operating
conditions, and desirably also following routine upsets such as stopping and
starting of the pump
such as to desirably provide pump seal and bearing protection under most
conditions except
catastrophic failure of the seal assembly. Accordingly, implementation of the
integrated
pressurized pump seal assembly according to one embodiment of the present
invention may
desirably reduce maintenance and outage costs to a pump user.
In a further embodiment of the present invention, an integrated pressurized
pump shaft
seal assembly for a rotary fluid pump is provided, where the integrated
pressurized pump shaft
seal assembly comprises: an oil reservoir; an integrated centrifugal oil pump
directly attached to
and rotatable by a pump shaft and fluidly connected to receive oil from the
oil reservoir; a seal
chamber fluidly connected to receive pressurized oil from the centrifugal oil
pump and
comprising: a pump shaft bearing adapted to be lubricated by said oil, and a
mechanical shaft
seal surrounding the pump shaft and adapted to seal the seal chamber against
ingress of a
pumped fluid. In another embodiment, the integrated pressurized pump shaft
seal assembly may
comprise first and second mechanical shaft seals.
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In another embodiment according to the present invention, a rotary fluid pump
comprising a pump motor, a pump shaft connected to said pump motor and a pump
impeller, and
further comprising an integrated pressurized pump shaft seal assembly adapted
for connection to
the pump shaft, where the integrated pressurized pump shaft seal assembly
comprises: an oil
reservoir; an integrated centrifugal oil pump directly attached to and
rotatable by a pump shaft
and fluidly connected to receive oil from the oil reservoir; a seal chamber
fluidly connected to
receive pressurized oil from the centrifugal oil pump and comprising: a pump
shaft bearing
adapted to be lubricated by said oil, and a mechanical shaft seal surrounding
the pump shaft and
adapted to seal the seal chamber against ingress of a pumped fluid.
In yet another embodiment according to the present invention, a method of
preventing
seal failure in a rotary fluid pump is provided, where the method comprises:
providing a rotary fluid pump comprising an integrated pressurized pump shaft
seal
assembly comprising: an oil reservoir; an integrated centrifugal oil pump
directly attached to and
rotatable by a putnp shaft and fluidly connected to receive oil from the oil
reservoir; a seal
chamber fluidly connected to receive pressurized oil from the centrifugal oil
pump and
comprising a pump shaft bearing adapted to be lubricated by said oil; and a
mechanical shaft seal
surrounding the pump shaft and adapted to seal the seal chamber against
ingress of a pumped
fluid; and
operating said rotary fluid pump by rotating said pump shaft with a pump motor
wherein
said pump shaft also directly rotates said integrated oil pump to pressurize
oil in said seal
chamber to prevent ingress of a pumped fluid into said seal chamber.
Further advantages of the invention will become apparent when considering the
drawings
in conjunction with the detailed description.
4. BRIEF DESCRIPTION OF THE DRAWINGS
The apparatus and methods of several embodiments of the present invention will
now be
described with reference to the accompanying drawing figures, in which:
FIG. 1 is a schematic view of an integrated pressurized pump shaft seal
according to an
embodiment of the present invention, and a pump apparatus comprising the same,
according to
another embodiment of the present invention.
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FIG. 2 is a longitudinal cross sectional view of an integrated pressurized
pump shaft seal
according to an embodiment of the present invention, which is part of a pump
apparatus
comprising the same, according to a further embodiment of the invention.
FIG. 3 is an inset longitudinal cross sectional view of internal details of an
integrated
pressurized pump shaft seal according to an embodiment of the present
invention, and part of a
pump apparatus comprising the same, according to a further embodiment of the
invention.
5. DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a schematic view of an integrated pressurized pump shaft
seal
assembly 102 is shown, according to an embodiment of the present invention,
and a pump
apparatus 100 is also shown comprising the same, according to another
embodiment of the
present invention. In one embodiment, the pump 100 may comprise a rotary
slurry or other fluid
pump such as for pumping one or more of fluids, fluid/solid suspensions and
slurries, for
example. In a particular embodiment, the pump 100 may comprise a submersible
and/or semi-
submersible pump such as a semi-submersible slurry pump for example, and may
comprise a
pump motor such as an electric pump motor 101, an integrated pressurized pump
shaft seal such
as integrated pressurized pump shaft seal assembly 102, and a pump
impeller/chamber assembly
or "wet end" 103, for example. In one such embodiment, the electric pump motor
101 may drive
the pump impeller assembly 103 through pump shaft 112, which may extend
through the
integrated pressurized pump shaft seal assembly 102, and may be supported by
upper shaft
bearings 118 and lower shaft bearings 108, for example.
In one embodiment, the integrated pressurized pump shaft seal assembly 102 may
comprise at least one mechanical shaft seal, such as a mechanical shaft seal
comprising upper
seal face 107 and lower seal face 117 which are located within a seal chamber
105 that surrounds
the upper seal face 107 and lower pump shaft bearings 108, and which is filled
with oil or other
suitable seal and/or bearing lubricating fluid. In a preferred embodiment, the
integrated
pressurized pump shaft seal assembly 102 comprises a dual mechanical seal
arrangement
comprising an upper mechanical seal 107, and a lower mechanical seal 117,
which each
comprise two mechanical seal faces engaged in rotational sealing contact with
each other to
provide a mechanical shaft seal on pump shaft 112. Mechanical seals 107, 117
may comprise
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any suitable mechanical seal design and/or materials, such as comprising
silicon and/or tungsten
carbide seal surfaces, for example, and in one embodiment of the present
invention, upper and
lower mechanical seals 107, 117 may each be provided as a cartridge mechanical
seal, for
example. Integrated pressurized pump shaft seal assembly 102 including
mechanical seals 107
and 117 and further comprising a seal chamber 105 containing oil (or any other
suitable seal
and/or bearing lubricating fluid for example) may desirably be pressurized at
a positive pressure
above the ambient or sump pressure outside the seal chamber 105 and may
therefore desirably
prevent a pumped slurry, fluid or other contaminants from a submerged pump wet
end 103 from
entering seal chamber 105 containing and protecting the lower shaft bearings
108, and protecting
the pump motor 101, for example. In one embodiment, the upper and lower
mechanical seals
107 and 117 may also desirably protect pump motor 101, and any other pump
components in the
"dry end" of the pump from exposure to a pumped slurry, fluid or other
contaminants from a
submerged pump wet end 103, for example.
In one embodiment, the integrated pressurized pump shaft seal assembly 102
further
comprises an oil pump 104 which may be desirably directly attached to and
integrated with the
pump shaft 112, such that the oil pump 104 is rotated and thereby powered
directly by the pump
shaft 112. In one embodiment, the oil pump 104 comprises a centrifugal
impeller pump 104,
such as a radial hole impeller pump, which is integrated with and rotated by
the pump shaft 112
and is operable to provide a positive oil pressure within the seal chamber
105, to desirably
pressurize seal chamber 105 to a desirably higher pressure than the
surrounding sump or pumped
fluid (such as a slurry) pressure inside the wet end 103 of the pump, or
outside the seal chamber
105, for example, such as to desirably exclude a pumped fluid such as a slurry
from entering the
seal chamber 105, the upper and lower mechanical seals 107 and 117, and to
desirably prevent
contamination of and/or damage to bearings 108, or pump motor 101, for
example. In one
particular embodiment, pressurized seal chamber 105 may desirably be
pressurized by oil pump
104 to a positive pressure of about 10 to 50 psi above the ambient pressure of
a pumped fluid
outside the seal chamber 105, such as the ambient pressure of pumped fluid or
slurry in wet end
103, for example. In one embodiment, integrated pressurized pump shaft seal
assembly 102
further comprises an oil reservoir 106, typically situated above seal chamber
105, and operable to
contain and supply oil (or another suitable seal and/or bearing lubricating
fluid) to oil pump 104,
to be pressurized and supplied to seal chamber 105 at a positive pressure
above the sump or
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external pressure of a pumped fluid or slurry outside of the seal chamber 105.
In a particular
embodiment, oil pump 104, such as a radial hole centrifugal impeller pump, may
be attached to
and integrated with pump shaft 112 such as by retaining oil pump 104 to shaft
112 by means of a
retaining locknut. In a further such embodiment, integrated oil pump 104,
bearings 108, and
optionally a shaft sleeve (not shown) may be attached to pump shaft 112 by a
common retaining
locknut, for example, such that rotation of the pump shaft 112 by pump motor
101 is operable to
rotate integrated oil pump 104. In a particular embodiment, bearings 108 may
be open to seal
chamber 105, such that oil or another suitable lubricating fluid pressurized
in chamber 105 by oil
pump 104 may provide lubrication to bearings 108. In a further such
embodiment, bearings 108
may comprise a bearing housing (not shown) which may desirably comprise a
bearing oil pool or
reservoir which may retain residual oil to lubricate bearings 108 even if seal
chamber 105 loses
pressure and is at least partly drained of oil, such as in the event of
failure of mechanical seals
107, 117, for example. In a particular embodiment, upper and lower mechanical
seals 107, 117,
may desirably be configured to sealingly accommodate a desired pressure
differential between
pressurized seal chamber 105 and the lower ambient pressure of a pumped fluid
outside the seal
chamber 105.
In one embodiment, integrated pressurized seal assembly 102 further comprises
a check
valve 109, located between integrated oil pump 104 and pressurized seal
housing 105. In a
particular such embodiment, check valve 109 may desirably be operable to
prevent backflow of
oil from seal chamber 105 to oil reservoir 106, through integrated oil puinp
104, such as may
otherwise occur upon shutdown of the pump motor 101, and may undesirably lead
to
contamination of oil reservoir 106 following eventual failure of mechanical
seals 107, 117, for
example. Since mechanical seals 107, 117 are subject to wear and eventual
failure upon
extended operation of pump 100, even with the assistance of pressurized seal
chamber 105 which
may desirably exclude pumped fluid (such as a pumped slurry) from entering
mechanical seals
107, 117 during normal operation, check valve 109 may also be operable to
close upon detection
of failure of lower mechanical seal 117, such as to keep pumped fluid and/or
moisture from
entering oil reservoir 106, such as through the integrated oil pump 104. In
one such
embodiment, check valve 109 may comprise a pressure-actuated valve such that
the check valve
109 closes if the pressure in the seal chamber 105 decreases below a desired
minimum pressure,
and whereby such closing of valve 109 may desirably reduce or prevent
admission of fluid to oil
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reservoir 106. In another such embodiment, a sensor (not shown) may be
provided that is
operable to detect failure of lower mechanical seal 117, and to trigger
closure of check valve 109
upon such failure. In another embodiment, a sensor may also be provided that
may trigger an
alarm or other suitable indication (such as an indicator light or signal for
example) to notify a
user of the failure of the lower mechanical seal 117. In a further optional
embodiment, one or
more sensors may also be provided to detect one or more of: failure of lower
or upper
mechanical seals 107, 117; low oil level in oil reservoir 106; water and/or
moisture ingress in to
seal chamber 105; and a drop in oil pressure in seal chamber 105 below a
desired minimum
level; faults, and such sensor(s) may further be operable to trigger an alarm
or other suitable
indication to notify a user of one or more of such faults.
In another embodiment of the present invention, the pump apparatus 100 may
additionally comprise a cooling jacket 111, such as for circulating oil (or
other suitable
lubricating fluid) from oil reservoir 106 under pressure from oil pump 104, to
cool pump motor
101 (such as a typical electric pump motor 101). In one such embodiment, such
as for use in a
semi-submerged pump, oil from oil reservoir 106 may be pumped into seal
chamber 105 by
integrated oil pump 104 driven by rotation of pump shaft 112, to pressurize
seal chamber 105 at
a positive pressure above an outside ambient fluid pressure, and a portion of
oil in seal chamber
105 may be admitted through a pressure reducing valve 110 (which may normally
be open) to
circulate cooling jacket 111 surrounding at least a portion of pump motor 101.
Such circulation
of oil from seal chamber 105 through pressure reducing valve 110 to cooling
jacket 111 and back
to oil reservoir 106 before returning to seal chamber 105 through oil pump
104, may desirably
circulate heat from pump motor 111 to seal chamber 105, where the circulated
oil may be cooled
by typically cooler surrounding ambient pumped fluid located outside of the
seal chamber 105.
In one such embodiment, pressure reducing valve 110 may desirably be
configured to maintain a
desired minimum positive pressure in seal chamber 105 such as by limiting
and/or controlling
flow of oil through valve 110 and cooling jacket 111, for example, to maintain
pressurization of
seal chamber 105 at or above the desired minimum positive pressure. In a
particular
embodiment, seal chamber 105 and any optional surrounding housing around seal
chamber 105
(not shown) may desirably be comprised of a suitably thermally conductive
material, such as
aluminum for example, so as to desirably allow dissipation of heat from oil in
seal chamber 105
(and optionally also from oil reservoir 106) to typically cooler pumped fluid
located outside of
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the chamber 105 and/or housing. In one such embodiment, walls of seal chamber
105 and/or a
further optional seal chamber housing may additionally include cooling fins or
other suitable
structures such as to improve heat dissipation from the oil chamber 105 to an
ambient fluid
outside of the chamber.
Similar to the check valve 109 described above, pressure reducing valve 110
may also be
operable to close upon detection of failure of lower mechanical seal 117, such
as to keep pumped
fluid and/or moisture from entering cooling jacket 111. In one such
embodiment, a sensor (not
shown) may be provided that is operable to detect failure of lower mechanical
seal 117, and to
trigger closure of pressure reducing valve 110 upon such failure. In another
embodiment, a
sensor may also be provided that may trigger an alarm or other suitable
indication (such as an
indicator light or signal for example) to notify a user of the failure of the
lower mechanical seal
117. In a further embodiment, following failure of the lower mechanical seal
117, the upper
mechanical seal 107 may desirably operate to prevent ingress of moisture,
pumped fluid or other
contaminants from entering the pump motor 101 and desirably also the seal
chamber 105 and
bearing 108 until the pump may be repaired and/or replaced. In another
embodiment, an
optional oil filter (not shown) may be provided such as between the seal
chamber 105 and the
check valve 109, or between the oil reservoir 106 and the oil pump 104, for
example, to desirably
provide additional protection against contamination of the oil in seal chamber
105 and provide
increased bearing life of bearings 108. In yet another embodiment, in a case
following failure of
both upper and lower mechanical seals 107, 117, the oil pump 104 may desirably
act as a
dynamic seal such as by pumping any fluid (such as including contaminating
pumped fluid or
other contaminants) entering the oil reservoir 106 back down to seal chamber
105, and away
from pump motor 101, thereby desirably preventing any such fluid from entering
and potentially
damaging pump motor 101 and desirably providing an additional protection
against pump motor
failure. In yet a further embodiment, in a case following interruption, upset
or power failure of
pump 100, integrated pressurized seal assembly 102 may desirably provide for
gradual reduction
of positive pressure within seal chamber 105 such as by providing for closure
of backflow valve
109 as pressure in seal chamber declines below a desired minimum pressure, and
thereafter by
allowing gradual bleed down of pressurized oil in seal chamber 105 through
mechanical seals
117, 107, so as to desirably maintain exclusion of a pumped fluid from the
seal chamber 105 and
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oil reservoir 106, for example, thereby protecting bearings 108 and pump motor
101,
respectively.
In one embodiment of the present invention, integrated pressurized seal
assembly 102
may further comprise a pressurized oil diffuser (not shown) such as located
between oil pump
104 impeller and pressurized seal chamber 105, so as to desirably convert
fluid velocity of oil
pumped by oil pump impeller 104 to static pressure for pressurizing seal
chamber 105 to a
desired positive pressure relative to outside ambient fluid pressure. In a
particular such
embodiment, integrated pressurized seal assembly 102 additionally comprises a
bearing housing
(not shown) within seal chamber 105 and containing shaft bearing 108, wherein
the bearing
housing includes a diffuser for receiving pressurized pumped oil from oil pump
impeller 104 and
converting fluid velocity of the pumped oil into static pressure within seal
chamber 105, for
example. In a further such embodiment, the diffuser may additionally include
at least one of
splitting and guiding channels (not shown) oriented to divert and/or direct
additional pumped oil
flow into pressure reducing valve 110 and thereby increasing oil flow to
cooling jacket 111, for
example. In another optional embodiment, oil pump 104 may additionally
comprise one or more
vent channels operable to vent a portion of oil pressurized by pump 104 to a
sump external to
seal chamber 105, such as to desirably reduce overpressure on seal chamber
105, for example.
In another embodiment of the present invention, seal chamber 105 may comprise
one or
more baffles or other suitable flow directing structures (not shown) effective
to desirably reduce
swirling and/or creation of air pockets or cavitation of pumped oil in the
vicinity of seal faces of
one or more of upper and lower mechanical seals 107, 117, for example. In an
optional
embodiment, oil pump 104, such as centrifugal radial impeller oil pump 104 may
desirably be
oriented in a direction such that an axial thrust load on pump shaft 112 due
to oil pump 104
integrated with pump shaft 112 may desirably act in a direction opposite to
one or more other
axial thrust loads on pump shaft 112, such as opposite to an axial thrust load
due to wet end 103
of putnp 100, such as to desirably reduce imbalance in axial thrust loads on
shaft 112 which may
be borne by bearings 108, 118, for example. In another embodiment directed to
pumps used for
submersion at significant depths in a pumped fluid, integrated pressurized
pump seal assembly
102 may desirably comprise a pressure compensation device (not shown) which is
operable to
desirably control or increase an operational oil pressure in pressurized seal
chamber 105, such as
to maintain a positive pressure of seal chamber 105 over an ambient pumped
fluid pressure
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outside seal chamber 105. In another optional embodiment, oil reservoir 106
may additionally
comprise an air relief valve (not shown), such as to relieve any aid in
reservoir 106, such as may
otherwise undesirably result in airlock of the oil reservoir/pump/seal chamber
oil pressurization
system of the assembly 102. In an alternative such embodiment, an air relief
valve may also
assist in adding oil to oil reservoir 106 such as to allow release of air from
oil reservoir 106 when
filling and/or refilling the assembly 102 with oil, for example. In yet
another alternative
embodiment, an air relief valve may admit air to reservoir 106 if desired, for
example.
In one embodiment of the present invention, a rotary fluid (and/or slurry)
pump 100
comprising an integrated pressurized pump shaft seal assembly 102 is provided,
wherein the
integrated pressurized seal assembly 102 is configured or otherwise adapted
for use with a
desired pump motor 101 and impeller assembly/wet end 103 to desirably provide
a pressurized
seal assembly to protect bearings 108 and pump motor 101, for example. In yet
another
embodiment of the present invention, a method of using a rotary fluid (and/or
slurry) pump 100
is provided where the pump 100 comprises an integrated pressurized pump shaft
seal assembly
102, and operation of the pump 100 such as by rotation of pump shaft 112 by
pump motor 101
also directly rotates integrated oil pump 104 so as to pressurize oil in seal
chamber 105 for
desirably preventing and/or reducing seal failure in pump 100. In a further
embodiment, a
method of preventing seal failure is provided, comprising providing a rotary
fluid (and/or slurry)
pump 100 comprising an integrated pressurized pump shaft seal assembly 102,
and operation of
the pump 100 such as by rotation of putnp shaft 112 by pump motor 101 also
directly rotates
integrated oil pump 104 so as to pressurize oil in seal chamber 105 for
desirably preventing
and/or reducing ingress of external fluids into seal chamber 105 and/or
mechanical seals 107,
117.
Referring now to FIG. 2, a longitudinal cross sectional view of a portion of a
rotary fluid
(and/or slurry) pump comprising an integrated pressurized pump shaft seal
assembly 200 is
shown. Similar to the embodiments of the present invention shown in schematic
form in FIG. 1,
integrated pressurized pump shaft seal assembly 200 comprises an integrated
centrifugal oil
pump 204 directly attached to and integrated with pump shaft 212, and situated
between an oil
reservoir 206 above integrated oil pump 204, and a seal chamber 205 containing
pump shaft
bearing 208 and situated below integrated oil pump 204. Integrated oil pump
204 is operable to
pump oil from oil reservoir 206 to seal chamber 205 to pressurize seal chamber
205 at a positive
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pressure greater than an ambient pumped fluid pressure outside seal chamber
205. In one
embodiment, the integrated pressurized pump shaft seal assembly 200 comprises
a dual
mechanical seal arrangement comprising an upper mechanical seal 207, and a
lower mechanical
seal 217, which each comprise two mechanical seal faces engaged in rotational
sealing contact
with each other to provide a mechanical shaft seal on pump shaft 212.
Mechanical seals 207,
217 may comprise any suitable mechanical seal design and/or materials, such as
comprising
silicon and/or tungsten carbide seal surfaces, for example, and in one
embodiment of the present
invention, upper and lower mechanical seals 207, 217 may each be provided as a
cartridge
mechanical seal, for example. Integrated pressurized pump shaft seal assembly
202 including
mechanical seals 207 and 217 and further comprising a seal chamber 205
containing oil (or any
other suitable seal and/or bearing lubricating fluid for example) may
desirably be pressurized at a
positive pressure above the ambient or sump pressure outside the seal chamber
205 and may
therefore desirably prevent a pumped slurry, fluid or other contaminants from
outside seal
chamber 205 from entering seal chamber 205 containing and protecting the lower
shaft bearings
208, and oil reservoir 206, and desirably also protecting the pump motor
located above the oil
reservoir 206, for example.
In a particular embodiment, oil pump 204 may comprise a radial hole
centrifugal impeller
pump, and may be directly attached to and integrated with pump shaft 212 such
as by retaining
oil pump 204 to shaft 212 by means of a retaining locknut, for example. In a
further such
embodiment, integrated oil pump 204, pump shaft bearings 208, and optionally
also a shaft
sleeve (not shown) may be attached to pump shaft 212 by a common retaining
locknut, for
example, such that rotation of the pump shaft 212 by a pump motor (not shown)
directly rotates
integrated oil pump 204. In a further embodiment, pump shaft bearings 208 may
be at least
substantially open to seal chamber 205, such that oil or another suitable
lubricating fluid
pressurized in chamber 205 by integrated oil pump 204 may provide lubrication
to bearings 208.
In a further such embodiment, bearings 208 may comprise a bearing housing (not
shown) which
may desirably comprise a bearing oil pool or reservoir which may retain
residual oil to lubricate
bearings 208 even if seal chamber 205 loses pressure and is at least partly
drained of oil, such as
in the event of failure of mechanical seals 207, 217, for example. In a
particular embodiment,
integrated pressurized pump shaft seal assembly 200 may also comprise at least
one lip seal 218
situated between oil reservoir 206 and pump shaft 212 which may desirably
provide a farther
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seal barrier between integrated pressurized pump shaft seal assembly 200 and a
pump motor
above assembly 202, and may desirably provide further protection for a pump
motor against
ingress of external fluids following failure of both mechanical seals 207,
217, for example.
In one embodiment, seal chamber 205 may further comprise a seal chamber
housing 220
such as to support mechanical seals 207, 217, and enclose seal chamber 205 and
pump shaft
bearings 208. In one such embodiment, seal chamber housing 220 may desirably
comprise a
suitable durable material with desirably high thermal conductivity, such as to
advantageously
provide for effective heat transfer from pressurized oil inside seal chamber
205 to a pumped fluid
(such as a pumped fluid in a sump, for example), which may desirably provide
for cooling of the
pressurized oil inside chamber 205, for example.
Referring now to FIG. 3, an inset longitudinal cross sectional view of
internal details of a
portion of a rotary fluid (and/or slurry) pump comprising an integrated
pressurized pump shaft
seal assembly 300 is shown. Similar to the embodiments of the present
invention shown in and
described above in FIG.s 1 and 2, integrated pressurized pump shaft seal
assembly 300
comprises an integrated centrifugal oil pump 304 directly attached to and
integrated with pump
shaft 312, and situated between an oil reservoir 306 above integrated oil pump
304, and a seal
chamber 305 containing pump shaft bearing 308 and situated below integrated
oil pump 304.
Integrated oil pump 304 is operable to pump oil from oil reservoir 306 to seal
chamber 305 to
pressurize seal chamber 305 at a positive pressure greater than an ambient
pumped fluid pressure
outside seal chamber 305, for example. In one embodiment, the integrated
pressurized pump
shaft seal assembly 300 comprises a dual mechanical seal arrangement
substantially similar to
that shown in FIG. 2 and described above, such as to allow for pressurizing
seal chamber 305
with oil (and/or another suitable bearing lubricating fluid for example) at a
positive pressure
above the ambient or sump pressure outside the seal chamber 305 and may
therefore desirably
prevent a pumped slurry, fluid or other contaminants from outside seal chamber
305 from
entering seal chamber 305 containing and protecting the lower shaft bearings
308, and oil
reservoir 306, and desirably also protecting the pump motor located above the
oil reservoir 306,
for example.
In a particular embodiment, oil pump 304 may comprise a radial hole
centrifugal impeller
pump, and may be directly attached to and integrated with pump shaft 312 such
as by retaining
oil pump 304 to shaft 312 by means of a retaining locknut, for example. In a
further such
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embodiment, integrated oil pump 304, pump shaft bearings 308, and optionally
also a shaft
sleeve (not shown) may be attached to pump shaft 312 by a common retaining
locknut, for
example, such that rotation of the pump shaft 312 by a pump motor directly
rotates integrated oil
pump 304. In a further embodiment, pump shaft bearings 308 may be at least
substantially open
to seal chamber 305, such that oil or another suitable lubricating fluid
pressurized in chamber
305 by integrated oil pump 304 may provide lubrication to bearings 308. In a
further such
embodiment, bearings 308 may comprise a bearing housing (not shown) which may
desirably
comprise a bearing oil pool or reservoir which may retain residual oil to
lubricate bearings 308
even if seal chamber 305 loses pressure and is at least partly drained of oil,
such as in the event
of failure of mechanical seals sealing the bottom of seal chamber 305, for
example. In a
particular embodiment, integrated pressurized pump shaft seal assembly 302 may
also comprise
at least one lip seal 325 situated between oil reservoir 306 and pump shaft
312 which may
desirably provide a further seal barrier between integrated pressurized pump
shaft seal assembly
300 and a pump motor above assembly 300, and may desirably provide further
protection for a
pump motor against ingress of external fluids following failure of mechanical
seals.
In one embodiment of the present invention, integrated pressurized seal
assembly 300
further comprises a check valve 309, located between integrated oil pump 304
and pressurized
seal housing 305. In a particular such embodiment, check valve 309 may
desirably be operable
to prevent backflow of oil from seal chamber 305 to oil reservoir 306, through
integrated oil
pump 304, such as may otherwise occur upon shutdown of the pump motor, and may
undesirably
lead to contamination of oil reservoir 306 following eventual failure of
mechanical seals below
seal chamber 305, for example. Since mechanical seals are subject to wear and
eventual failure
upon extended operation of a rotary pump, particularly in harsh operation such
as in pumping
abrasive slurries, even with the assistance of pressurized seal chamber 305
which may desirably
exclude pumped fluid (such as a pumped slurry) from entering mechanical seals
during normal
operation, check valve 309 may also be operable to close upon detection of
failure of a
mechanical seal, such as to keep pumped fluid and/or moisture from entering
oil reservoir 306,
such as through the integrated oil pump 304. In one such embodiment, check
valve 309 may
comprise a pressure-actuated valve such that the check valve 309 closes if the
pressure in the seal
chamber 305 decreases below a desired minimum pressure, and whereby such
closing of valve
309 may desirably reduce or prevent admission of fluid to oil reservoir 306.
In another such
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embodiment, a sensor (not shown) may be provided that is operable to detect
failure of a
mechanical seal below chamber 305, and to trigger closure of check valve 309
upon such failure.
In another embodiment, a sensor may also be provided that may trigger an alarm
or other
suitable indication (such as an indicator light or signal for example) to
notify a user of the failure
of a mechanical seal. In a further optional embodiment, one or more sensors
may also be
provided to detect one or more of: failure of mechanical seals (not shown);
low oil level in oil
reservoir 306; water and/or moisture ingress in to seal chamber 305; and a
drop in oil pressure in
seal chamber 305 below a desired minimum level; faults, and such sensor(s) may
further be
operable to trigger an alarm or other suitable indication to notify a user of
one or more of such
faults.
In another embodiment of the present invention, the integrated pressurized
pump seal
assembly 300 may additionally comprise a cooling jacket 322, such as for
circulating oil (or
other suitable lubricating fluid) from oil reservoir 306 under pressure from
oil pump 304, to cool
a pump motor (desirably located at least partially within cooling jacket 322).
In one such
embodiment, such as for use in a semi-submerged pump, oil from oil reservoir
306 may be
pumped into seal chamber 305 by integrated oil pump 304 driven by rotation of
pump shaft 312,
to pressurize seal chamber 305 at a positive pressure above an outside ambient
fluid pressure,
and a portion of oil in seal chamber 305 may be admitted through a pressure
reducing valve 310
(which may normally be open) to circulate through cooling jacket 322
surrounding at least a
portion of the pump motor. Such circulation of oil from seal chamber 305
through pressure
reducing valve 310 and thereafter through a cooling oil supply conduit 327 to
cooling jacket 322,
then through returning to oil reservoir 306 through cooling oil return conduit
328, before
returning to seal chamber 305 under pressure from integrated oil pump 304, may
desirably
circulate heat from the pump motor to seal chamber 305, where the circulated
oil may be cooled
by typically cooler surrounding ambient pumped fluid located outside of the
seal chamber 305,
such as in sump 329, for example. In one such embodiment, pressure reducing
valve 310 may
desirably be configured to maintain a desired minimum positive pressure in
seal chamber 305
such as by limiting and/or controlling flow of oil through pressure reducing
valve 310 and
cooling jacket 322, for example, to maintain pressurization of seal chamber
305 at or above the
desired minimum positive pressure. In a particular embodiment, seal chamber
305 and any
optional surrounding housing around seal chamber 305 (not shown) may desirably
be comprised
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of a suitably thermally conductive material, such as aluminum for example, so
as to desirably
allow dissipation of heat from oil in seal chamber 305 (and optionally also
from oil reservoir
306) to typically cooler pumped fluid located outside of the chamber 305
and/or housing, such as
a pumped fluid in sump 329. In one such embodiment, walls of seal chamber 305
and/or a
further optional seal chamber housing may additionally include cooling fins or
other suitable
structures such as to improve heat dissipation from the oil chamber 305 to an
ambient fluid
outside of the chamber.
Similar to the check valve 309 described above, pressure reducing valve 310
may also be
operable to close upon detection of failure of a mechanical seal below seal
chamber 305, such as
to keep pumped fluid and/or moisture from entering cooling jacket 322. In one
such
embodiment, a sensor (not shown) may be provided that is operable to detect
failure of a
mechanical seal below seal chamber 305, and to trigger closure of pressure
reducing valve 310
upon such failure. In another embodiment, a sensor may also be provided that
may trigger an
alarm or other suitable indication (such as an indicator light or signal for
example) to notify a
user of the failure of a mechanical seal. In an optional, an optional oil
filter (not shown) may be
provided such as between the seal chamber 305 and the check valve 309, or
between the oil
reservoir 306 and the oil pump 304, for example, to desirably provide
additional protection
against contamination of the oil in seal chamber 305 and provide increased
bearing life of
bearings 308.
The exemplary embodiments herein described are not intended to be exhaustive
or to
limit the scope of the invention to the precise forms disclosed. They are
chosen and described to
explain the principles of the invention and its application and practical use
to allow others skilled
in the art to comprehend its teachings.
As will be apparent to those skilled in the art in light of the foregoing
disclosure, many
alterations and modifications are possible in the practice of this invention
without departing from
the scope thereof.
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